I'm only comfortable below 25 Celsius, and in the past that was a significant factor for me to decide when to wear.
Besides diapers by nature aren't really the most efficient garment in dissipating heat, though some setups are better than others.
My experience has occurred in less extreme circumstances than those of some other people (namely, i can decide whether to wear a diaper or not, and my town's climate, while being classified as "subtropical" according to Koppen, can't really be compared to places like Phoenix, L.A.or Houston), but here are my observations, for what they might be worth:
-Using air conditioning for a couple hours really helps me recover, and not feel overwhelmed by heat - ceiling fans, not so much.
I've experienced that this feels especially important in the evening and in the morning, when waking up, but I didn't find that to be as important in other times of the day, every if during those times it's actually hotter.
-I fully subscribe to the suggestion about bright colored, loose clothes.
If you only wear at home you might also consider to only wear a diaper and a loose shirt, even better a sleeveless one.
As I'm writing this I'm wearing some very skimpy runner shorts, the kind that normally would only cover your undergarments and little else.If I'm wearing a diaper and those shorts the sides of the diaper would peek from the leg holes, but personally that isn't a big issue. I'd never go out wearing these and a diaper, though.
Why I'm mentioning my shorts? Because by wearing them I can feel just as much as ventilated as I would if I only wore my pants, or diaper, while actually having something to cover them up and mantain a measure of decency.
-I never found cloth backed to be an improvement, rather I discovered that I actually sweat more in them.
-But, as I stated, I don't like to feel much heat down there, and for me a full plastic diaper feels generally uncomfortable, and like torture in summer.
On the other hand, I've found my equilibrium by wearing diapers that have breathable (i.e. non-wowen) wings, but are otherwise plastic backed.I'm probably very sensitive to heat and perspiration around my hips, while not as much in the other areas a diaper would cover.
Experiment with it, though your mileage may vary.
-If you need to use a booster or a liner for additional absorbency or feel, please consider using a liner: i wore my diapers with thin, store brand, plastic backed rectangular inserts until recently, but recently bought a pack of liners: I've found out that while the liners were thicker and had firmer padding somehow diaper felt much more breathable using them.
Hopefully you will find what works for you.
Summer and diapers could and should fit into the same sentence, regardless of what specific motivation you have to wear them.
Best of luck!
